A cutting tool having a cutting edge portion formed of a so-called ultrahigh-pressure sintered compact is conventionally known. Such a cutting tool is fit for use in cutting of high hardness materials such as hardened steel, carburized steel and so on, cutting of cast iron and cast steel, cutting of sintered metals, high-speed cutting of nonferrous metals such as an aluminum alloy and the like, and the like.
One of the conventional cutting tools with ultrahigh-pressure sintered compact in the related art is described in PTL 1. The cutting tool described in PTL 1 has a cutting edge member formed of an ultrahigh-pressure sintered compact containing at least one of diamond and Cubic Boron Nitride. A rake surface is formed on the upper surface of the cutting edge member. A flank is formed on the periphery of the cutting edge member. A cutting edge having an arc-shaped corner cutting edge is formed at the intersection of the rake face and the flank. On the surface of the cutting edge member, two breaker wall surfaces are formed in such a manner as to intersect with each other on the bisector of a corner portion in which the aforementioned corner cutting edge is placed. Further, a distal-end breaker surface is formed on the intersecting portion of the two breaker wall surfaces to be pointed at the leading end side of the corner portion in order to improve the chip treatability.